>The only downside that I see to this is that such creation would>require effort to the tune of tens of millions of dollars (and then>a lot more still).

WHAT?!?! Tens of millions of dollars?! We can create the world in simple
VRML now and as the language improves we can simply gradually add more
detail. We could store textures, and rooms all over the net on volunteer's
personal webspace provided by their ISPs or volunteer webservers. It's not
like we need to hire people to do this. We can do this ourselves.